In late 2010, Grupa LOTOS SA completed construction of a major residue-upgrading project at its refinery in Gdańsk, Poland. Its 10+ Program was designed to unlock a step change in the facility’s long-term profitability. After two years of operating, this project has had a profound effect on the refinery’s economics.

In late 2010, Grupa LOTOS SA completed construction of a major
residue-upgrading project at its refinery in Gdańsk,
Poland. Its 10+ Program was designed to unlock a step change in
the facilitys long-term profitability. After two years of
operating, this project has had a profound effect on
the refinerys economics. Following the project, the refinery increased its crude
capacity by 75% to 10 million tpy, achieved higher conversion
capacity, and improved margins by $5/bbl. In addition, Grupa
LOTOS was able to increase production of higher-margin jet fuel
and diesel, while reducing fuel oil production (Fig.
1). Result: The refiner moved closer
to its goal of securing the complexs future in response
to increasingly stringent fuel specifications and emissions legislation.

Fig.
1. Side view of the Grupa
LOTOS
residue-upgrading complex.

Two key process units of the new residue-upgrading complex
included an advanced solvent deasphalter and
residuum/distillate hydrocracker. The new hydrocracker could
process a blend of deasphalted oil (DAO) and vacuum gasoil
(VGO).1 In addition, the DAO hydrocracker used
state-of-the-art reactor internals and commercially proven
demetallization, hydrotreating and hydrocracking
catalysts.2 The hydrocracker successfully completed
its acceptance test run in May 2011 and has met all performance
guarantees.

With the initial cycle now close to two years, the unit has
delivered sustained performance in converting the DAO/VGO feedstock directly into Jet A-1 fuel
and Euro 5-quality diesel, both with sulfur contents much lower
than 10 ppm. Additionally, Grupa LOTOS worked with the
hydrocracker licensor and catalyst provider to optimize the DAO
hydrocrackers performance. The net conversion increased
from the original design level of 60% in once-through mode to
80% conversion in recycle mode. These changes have raised
middle-distillate yields, while operating within the
refinerys hydrogen availability.

Grupa LOTOS experience integrated the new
residue-upgrading complex with minimal modifications to the
existing main infrastructure of the refinery.1 The
advanced solvent deasphalting unit requires feedstock
(atmospheric or vacuum residue) plus utilities from the
refinery. It produces DAO, which is sent directly to the
hydrocracker, and an asphaltene liquid residue, which can be
sent to fuel oil or asphalt blending, a pelletizing unit or a
boiler for power production. There are no large product streams
requiring further processing or treating.

The DAO hydrocracker requires feedstock (VGO, DAO and
hydrogen) and produces finished products, mostly jet fuel and
diesel. It also yields hydrowax, which Grupa LOTOS uses as a
feed for base-oil manufacturing and as a component for
low-sulfur fuel oil (LSFO). The unit also produces some light
naphtha. Grupa LOTOS sends most of the naphtha to the
isomerization process, although it could also be sent directly
to gasoline blending. The heavy naphtha is used as catalytic
reformer feed, although this can also be sold as chemical
feedstock. Grupa LOTOS uses the asphaltene residue in the
production of heavy-sulfur fuel oil (HSFO) and for bitumen
blending. Fig. 2 is a simplified block scheme
of the new residue-upgrading units installed at Grupa
LOTOS.

The project team had to consider
numerous counterbalancing aspects when developing the reactor
configuration and process design. For instance, although it was
desirable to maximize the solvent deasphalter units DAO
yield and the hydrocracker conversion level, this led to higher
metals and Conradson carbon residue (CCR) content. This
route required larger volumes of catalyst, especially
demetallization catalyst; it also required larger reactors to
achieve an economically viable catalyst run length. The
hydrocracker licensor, catalyst provider and Grupa LOTOS worked
closely together to find the best design that would optimize
the returns against the cost. As shown in Fig.
3, the DAO hydrocracker features three in-series
reactors designed for sequential processing of the feedstock
into finished products. These reactors are the:

Fig.
3. DAO hydrocracker
configuration.1

Demetallization reactor, which reduces metals in feed to
less than 1 ppmw

Pretreatment reactor, which reduces key contaminants such
as nitrogen, sulfur and CCR

Cracking reactor, which is designed to achieve target
conversion and to produce on-specification liquid
products.

The DAO hydrocracker at Grupa LOTOS has a capacity of 6,000
tpd (2 million tpy), a catalyst cycle length of a minimum of
three years and a net conversion level of 60%, which has
increased to 80%. The units hydrogen consumption is
within the availability from the refinerys hydrogen
manufacturing unit. Most of the produced naphtha feeds the
gasoline production units; the remainder is sold as chemical
feed.

From almost two years of monitoring data, the unit has
achieved sustained performance, and it has overachieved in
terms of yield and catalyst life. In addition, the catalyst
deactivation is very slow and it is on target for the next
planned turnaround. Yields are also stable, as is product
quality. Since the startup of the new units, Grupa LOTOS,
working closely with technical services from the hydrocracker
licensor and catalyst providers, adjusted the operation of the
hydrocracker to increase jet fuel and diesel production and to
minimize unconverted residue make.1, 2

Middle-distillate selectivity was a key consideration; it
prevented higher conversion in the once-through operation. To
overcome this condition, recycle of the fractionator bottoms
(unconverted residue) was implemented, and the conversion was
successfully raised from 60% to 80%. DAO yield from the
advanced solvent deasphater unit, and, therefore, the
percentage of DAO in the hydrocracker feed, has steadily
increased in line with the hydrocrackers ability to
process more difficult feed with higher metals, nitrogen and
CCR content. All of these changes were made in incremental
steps and closely monitored.

Demetallization catalyst performance

Feed metals reduction is the most critical performance
specification for the demetallization catalyst system, as this
determines its ability to achieve a feed quality to the
pretreatment catalyst that is more consistent with that of a
very heavy VGO feed. The demetallization catalysts installed at
Gdańsk are specialty demetallization catalysts that have a
very high activity for metals removal, a high metal uptake
capacity, and a high crush strength.3 These
catalysts are used extensively for:

Removing metals and CCR in the upgrading of heavy VGOs,
residues and DAO

Protecting the pretreatment catalyst from metal poisoning
in the guard bed or reactor of a multi-reactor system.

The deactivation rate of the demetallization catalyst has
been low and is on target for the planned cycle length and
turnaround date. As shown in Fig. 4 (blue
series), the demetallization removal efficiency has been near
100% over the cycle. The DAO hydrocracker design allows the
ability to safely obtain a sample of the demetallization
reactor effluent and to directly measure the metal slip to the
pretreatment catalyst. The accumulation rate of metals on
catalyst is calculated and closely monitored on the basis of
real performance data. The trend of total metals on catalyst is
in line with the plan, as shown in Fig. 4 (red
series). From the sampling program across the demetallization
reactor, after nearly two years of operation, the
demetallization catalyst continued to achieve significant
conversion levels of sulfur (approximately 90%), CCR (80%) and
nitrogen (50%). In addition to metals removal, the system has
unlocked pretreatment catalyst activity and enabled further feedstock optimization.

Pretreatment and cracking catalyst performance

The pretreatment and cracking catalysts are applied in a
stacked-bed system over multiple beds across the two
reactors.2 This system contains:

A high-activity nickel (Ni) molybdenum (Mo) catalyst,
which has an exceptionally high hydrodesulfurization (HDS)
activity and high-metals tolerance2

A dual-function, HDS/hydrodenitrogenation (HDN) active,
mild conversion catalyst, which is applied in the bottom beds
of pretreatment service2

Middle-distillate-selective cracking
catalysts.2

This catalyst system, which has been proven commercially in
many VGO hydrocracking and fluid-catalytic cracking (FCC)
pretreatment applications processing heavy feeds, has shown
very stable performance. The activity and selectivity closely
match the original performance estimates, and the product
qualities of the middle-distillate streams (kerosine and
diesel) continue to meet and even exceed specifications.

After a brief initial operation at near-design conditions,
the net conversion of the hydrocracker was increased to 80%
over the course of the first year of operation. As shown in
Fig. 5, the net conversion has remained close
to the 80% level, even as the feed quality has changed with
increased nitrogen and CCR content, owing to the higher DAO
lift in the advanced deasphalter unit and higher DAO level in
the hydrocracker feed blend. Despite this increased severity,
the DAO hydrocracker has delivered sustained performance over
almost two years of operation. The kerosine product
continuously achieves full Jet A-1 fuel quality requirements
and significantly exceeds the 25-mm smoke-point specification,
as shown in Fig. 6. Similarly, the diesel
product has been achieving full Euro 5 quality requirements and
significantly exceeding the 46 cetane index specification, as
shown in Fig. 7. Significantly, both
distillate products continue to have very low sulfur levels,
below 2 ppmw and well below the 10-ppmw specification for
diesel product, as shown in Fig. 8.

Fig.
5. Net conversion levels achieved by
the
DAO hydrocracker.

Fig.
6. Kerosine smoke point.

Fig.
7. Diesel cetane index.

Fig.
8. Kerosine and diesel sulfur
content.

With the advanced solvent deasphalter, the design of the DAO
hydrocracker offers the refinery more flexibility. From a feedstock perspective, different
crude blends are possible while still controlling fuel-oil
production. From a refined-product optimization perspective,
this refinery is able to use the high-quality kerosine as a
blending component to increase diesel production; to adjust
diesel cold-flow properties; or to be sold as Jet A-1 fuel,
depending on the market conditions.

The fractionator bottoms, called hydrowax or unconverted
residue, form a high-quality product due to the high-hydrogen
and low-sulfur contents and absence of CCR species. A
profitable outlet for the hydrowax has been as supplemental
feed to the base-oil plant at the Gdańsk refinery, which
has improved yields and increased quality of the base-oil
products. Hydrowax is also blended into LSFO. In an FCC-based
refinery, the low-sulfur content of
the hydrowax (below 50 ppm) enables gasoline production from an
FCC unit, co-processing the hydrowax, to meet the 10-ppm sulfur
gasoline specification more easily.

Grupa LOTOS looks to the future

Grupa LOTOS launched the 10+ Program in response to
increasingly stringent product specifications that were
threatening its competitiveness. The rewards that it has
unlocked are compelling. Based on this success, Grupa LOTOS has
commenced the next chapter in its performance improvement
journey. The refiner plans to eliminate all liquid fuel residue
and provide the best fit with respect to the strategic drivers
and return on investment. HP

Desiree de Haan works in
hydrocracking technical service at Criterion Catalysts
& Technologies and covers units in the EMEAR region.
She has worked at the Shell Research and Technology Centre in
Amsterdam, The Netherlands, and with Criterion for
several years in catalyst research and development and
technical service in the fields of distillate
hydrotreating, fluidized catalytic cracking pretreatment
and (mild) hydrocracking. Ms. de Haan holds an MSc degree
in inorganic chemistry and catalysis from Utrecht
University, The Netherlands.

Mike Street is a principal process
engineer at Shell Global Solutions in Amsterdam, The
Netherlands. He is primarily responsible for Shells
hydrocracking design and technical services in the EMEAR
region. Mr. Street has more than 20 years of experience
in refining design, operation and
technical services, mostly in hydrocracking. He holds a
BSc degree in chemical engineering from the University of
Birmingham, UK.

Grzegorz Orzeszko works in Grupa
LOTOS hydrocracking department, covering the
operation of VGO and DAO hydrocracking units. He has
worked in Grupa LOTOS investment department (10+
Program) for five years and was responsible for the
Shell Global Solutions DAO hydrocracker from initial
basis of design through the investment process to
startup. Mr. Orzeszko holds an MS degree in chemical
technology from AGH University of Science and Technology, Kraków,
Poland.

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